The invention relates to a microflotation system with a flotation tank in which dispersion water enriched with a gas is introduced through a dispersion water feed line in which an expansion valve is arranged. In the expansion of the dispersion water, microbubbles form which slowly rise in the flotation tank and collect on impurities and transport them to the surface of the flotation tank. Such microflotation systems are suitable for purifying a wide range of wastewaters and are distinguished in principle by largely service-free and economical operation.
With most known microflotation systems, the amount of dispersion water supplied to the flotation tank can be adjusted by a one-time setting of an expansion valve. According to a guide value, approximately 10 L of dispersion water per kilogram solid content in the waste water must be supplied for satisfactory purification.
From U.S. Pat. No. 5,693,222, it is known to measure cloudiness of the wastewater purified in a microflotation system and, in the event of strong cloudiness, to actuate an expansion valve so that more gas is supplied. An optimum gas/solid ratio is thereby pursued.
Against this background, it is the object of the invention to provide a microflotation system that produces an optimum purification effect under changing operating conditions while working very efficiently, as well as a corresponding method for operating a microflotation system.